I have read the old posts and can't find anything that answers my question.

The situation I have in the Silver car is an amp gauge that is reading approximately 25 amps of charging while driving. My voltage regulator is not allowing over charging I have approximately 14.7 volts going to the battery. I have clean terminals at the junction box on the radiator support. My horn relay does work regarding the horn but the key buzzer does not work. Not sure if there is circuitry in the horn relay that could cause this overcharge. Any troubleshooting ideas are welcomed.

Check ALL your grounds. P=IxE where power is expressed in watts, voltage is the "push" (E) I is current measured in Amps ( what's being used) A bad ground will impose an increased load in the circuit. Just as dirty connections increase resistance ,also increasing total load(or impedance) in the circuit----Does amperage vary with accessories being turned on/off ?With just the engine running ,only the coil should be drawing. Or be your biggest draw. Try using another meter in line bypassing your gauge and compare readings. My luck has always been with bad grounds. How are your body/chassis ? If not so simple, you can pull fuses isolating circuits and measure readings. Just one approach--surely others will chime in.

Which is better for monitoring a vehicle's electrical system - a Voltmeter or an Ammeter?

Short answer:

A voltmeter, by far.

Electrical guru Mark Hamilton of M.A.D. Enterprises points out that amperage is a measure of current flow, so an ammeter is actually a "flow meter" that's intended to measure current flow to the battery (under normal conditions) or discharge from the battery (in the case of alternator system failure). On a typical flow meter, all output must be directed through the device to obtain an accurate reading. In the ammeter's case, that means all the alternator output used to recharge the battery must first be routed through the ammeter under the dash. Which requires a heavy-gauge cable and presents a possible fire hazard. And the ammeter itself must be able to handle all this current flow, so it must have a higher current rating than the alternator's maximum rated output.

All this might be worth the hassle if the ammeter produced reliable information. But the ammeter can only measure the amount of current output to the battery for recharging purposes: When the alternator recharges a "low" battery, the ammeter indicates a high charge rate; with a fully charged battery the voltage regulator reduces alternator output, and the ammeter is supposed to indicate a very low charge rate. But how can you really tell the regulator has reduced alternator output because the battery is fully charged? Maybe a diode in the alternator rectifier failed, or the alternator belt slipped after it warmed up, just as if the battery were fully charged. Or maybe the meter indicates a medium charge rate most of the time-does the battery want this much or could the voltage regulator be overcharging the battery?

On the other hand, a voltmeter works like a fuel pressure gauge-but instead of measuring fluid in psi, the voltmeter measures electrical system pressure in volts. Just like a fuel pressure gauge, a voltmeter only needs to tap into a circuit; all the fuel (or electricity) does not have to detour through the gauge itself. Voltmeter installation is easy, quick, and safe: It hooks up to a fused, ignition-switched "off/on" source and does not require any modification of the circuit used to recharge the battery or any part of the alternator/regulator system. In short, the voltmeter installed at the dash will be a stand-alone circuit.

The voltmeter directly measures the result of charging-system performance. With normal alternator/voltage-regulator function, battery voltage is maintained at 14.0 to 14.5 volts-and this is reported directly by the voltmeter. In the event of alternator-system failure, voltage will be low and continue to drop as the battery discharges. In the event of an "overcharge" condition, the voltmeter will climb above its normal zone. In summary, there is no chance for misinterpreting a voltmeter's readings as can happen with an ammeter.

Voltmeter vs. Ammeter?

Auto Meter offers both, but for most applications a voltmeter yields a safer installation while providing more useful information on charging-system conditions.

Not debating ,just some info on the ammeter's function---hope it helps.

It's not unusual for an amp gauge to read high if the battery is (at least) partially discharged. And it may take 40 to 50 miles of freeway driving to get it back to normal. How old is the battery? When was the last time you drove the car? Was it freeway miles or local roads? You have to take all this into consideration before you start diagnosing.

Check ALL your grounds. P=IxE where power is expressed in watts, voltage is the "push" (E) I is current measured in Amps ( what's being used) A bad ground will impose an increased load in the circuit. Just as dirty connections increase resistance ,also increasing total load(or impedance) in the circuit----Does amperage vary with accessories being turned on/off ?With just the engine running ,only the coil should be drawing. Or be your biggest draw. Try using another meter in line bypassing your gauge and compare readings. My luck has always been with bad grounds. How are your body/chassis ? If not so simple, you can pull fuses isolating circuits and measure readings. Just one approach--surely others will chime in.

The amp gauge will go down under load. While idling the amp gauge does read lower than while driving down the road.I will check the body grounds.

It's not unusual for an amp gauge to read high if the battery is (at least) partially discharged. And it may take 40 to 50 miles of freeway driving to get it back to normal. How old is the battery? When was the last time you drove the car? Was it freeway miles or local roads? You have to take all this into consideration before you start diagnosing.

Ed

I have driven the car a few hundred miles off and on with 20 miles of freeway driving. I feel confident I have driven enough to give the battery time to charge. HOWEVER, the battery in the car is a cheapo wrong size battery that was in the car when I bought it. It is only 12 months old but I will go have it checked and perhaps the battery has a bad cell or such.

On factory gauges a good start is checking the accuracy of the gauge. Either run a handheld and compare readings, or take the unit to a reputable shop that can test the gauge. I remember going back to the dealer with a friend who's new chevy meter was reading very high. The dealer checked the output, replied it was fine, "don't worry about the numbers, worry if it changes from it's norm".

Also remember that the factory gauge is NOT an "ammeter" - it's not in series with any loads; it's simply a sensitive voltmeter (galvanometer) that senses the voltage at the starter solenoid and at the horn relay screw terminal buss, compares them, and displays the difference as "amp numbers", to indicate whether current is flowing TO or FROM the battery. The last "ammeter" in a GM car was in the '62 Corvette.

Ah ,the old "cheapo battery" Keep in mind the alternator is really not designed to be a battery charger but replace what is "taken out" of the battery so to speak during operation. On a side note I remember my father had nothing but positives to state when internally regulated alternators became mainstream. I think only negative was no forgiveness if shorted--diodes done.

As far as grounding ,on the race car all my circuit grounds lead to a common brass terminal/bus bar which wires direct to the battery. Charging system: alternator-volt meter-battery. Overkill but effective.

Also remember that the factory gauge is NOT an "ammeter" - it's not in series with any loads; it's simply a sensitive voltmeter (galvanometer) that senses the voltage at the starter solenoid and at the horn relay screw terminal buss, compares them, and displays the difference as "amp numbers", to indicate whether current is flowing TO or FROM the battery. The last "ammeter" in a GM car was in the '62 Corvette.

The amp meter (really a volt meter) is reading the voltage drop across two points (which act as a shunt). I believe the two points are the horn relay and the terminal block by the battery. The wire between those points has a fixed resistance(acts as a shunt like all amp meters). As the current increases through that wire, a voltage drop is measured (IxR). The voltage drop is in proportion to the amplitude of current flowing between those two points. The meter is calibrated to represent amperage.

Agree with most answers given. The OE ammeter is a millivoltmeter measuring a voltage drop on a length of wire.The OE ammeter is merely an indicator, no quantitative measurements, read calibrated, can be trusted.A true ammeter measures the current draw to/from the battery.A suggestion would be installing temporarly an ammeter with an internal shunt, a cheap -50-0-+50 ammeter from Harbor Freight, catch on sale for $10 or less, can be wired up to the two leads on the battery junction block. Hook up ammeter, turn on lights, gauge reads towards the charge side, reverse the leads.

With 25 amps indicated all the time, it may be a bad battery cell - swap a known good battery and compare results.After a normal engine start, with OE designed circuitry, it would take about 15-20 miles of 2000-2500 rpm to recharge fullyAlso, with 25 amps, it is getting close to the max output for a 37 amp alternator. I would imagine the alt case is hot to the touch.Tip: with a 50 amp range of the HF ammeter, you could hook it up to the alt BATT stud and view the action.

Also if you changed the size or length of the charging lead from the horn relay to the terminal block infront of the battery the scale of the meter will be completely off. The gauge is calibrated for the stock wire size. Larger wire, lower change for the same amount of current, smaller wire larger change for the same current. If the connections at the end of the ammeter wires are corroded or loose that will cause a higher reading as well.